The invention herein resides in the art of aircraft brakes and, more particularly to those employing brake disk stacks or heat sinks comprised of alternately interleaved stator and rotor disks. More particularly, the invention relates to a back plate configured for such brake disk stacks. Specifically, the invention relates to a conical back plate connected to a torque tube and extending from the outboard end thereof, the conical back plate being stiffened and reinforced by the unique positioning of rings at truncated ends thereof.
Aircraft brakes typically consist of a stack or heat sink of alternately interleaved stator and rotor disks. The stator disks are mounted upon a torque tube and are axially movable thereon. The rotor disks are keyed to the aircraft wheel both axially movable thereon and rotatable therewith. Accordingly, the brake disk stack comprises alternately interleaved rotor disks that rotate with the wheel and stator disks that are non-rotatable. At one end of the stack, a pressure plate is provided for actuation by appropriate pistons that are hydraulically or electrically actuated. At the opposite end of the stack, a stationary back plate is maintained. Accordingly, actuation of the pressure plate by the pistons urges the stators and rotors into frictional contacting engagement with each other against the stationary back plate. Those skilled in the art will appreciate that the back plate receives all of the compressive braking force associated with the brake disk stack.
It is well known that considerations of weight are paramount in aircraft designs. It is most desirable to minimize the weight of every structure associated with the aircraft to improve the efficiency and load bearing capabilities of the aircraft. Accordingly, while the back plate of the brake disk stack may be a solid planar plate, such plate imparts significant and unnecessary mass to the brake disk stack. In the past, the art has evolved to a metallic conical back plate extending from the outboard end of the torque tube and in the form of a truncated cone. This conical back plate receives and withstands the axial brake force imparted to the brake disk stack, and does so by withstanding the tension imparted therein. Accordingly, back plates of a truncated conical nature primarily serve as a membrane placed in tension by the braking force. Since this conical membrane is necessarily as thin as possible to satisfy necessary weight constraints, concern must be given that bending or deflection of the membrane of the backup plate is minimized. In that regard, reinforcing rings have been interposed at the inboard and outboard ends of the conical backup plate to impart compressive forces to the conical member, thus reinforcing that member by stiffening it. It has been found that such compressive stiffening substantially reduces the bending or deflection otherwise experienced thereby.
In the past, it was believed that the optimum positioning of the reinforcing rings at the opposite ends of the conical back plate was to position the rings with their cross sectional centers of mass generally geometrically aligned with a cross sectional center line of the conical member itself. But, such positioning has now been found to result in less than an optimum reduction of bending and deflection in the conical member. Accordingly, there is a need for a torque tube and conical back plate assembly in which the positioning of the reinforcing rings at opposite ends of the conical back plate is such as to optimize such reinforcement to prevent bending and deflection, while allowing for reduction in the mass of the metallic conical member itself, thus further reducing the weight of the brake assembly, without sacrificing integrity.
In light of the foregoing, it is a first aspect of the invention to provide a torque tube and conical back plate for aircraft brakes which provides enhanced strength and reinforcement against bending and deflection as compared to prior art structures.
Another aspect of the invention is the provision of a torque tube and conical back plate for aircraft brakes which allows for weight reduction in the brake assembly, without a reduction in performance or integrity.
Yet a further aspect of the invention is the provision of a torque tube and conical back plate for aircraft brakes wherein reinforcing rings are provided at the truncated ends of the conical back plate and are moved axially outboard such that their center of mass is outboard of a projection of the center cone of the conical member.
Yet a further aspect of the invention is the provision of a torque tube and conical back plate for aircraft brakes which optimizes strength and integrity of the conical back plate without an increase in weight.
The foregoing and other aspects of the invention which will become apparent as the detailed description proceeds are achieved by a torque tube and conical back plate assembly for aircraft brakes, comprising: a torque tube for receiving stator disks of a brake disk stack, said torque tube having an inboard end and an outboard end with respect to an orientation of mounting on an aircraft; a conical back plate extending from an outboard end of said torque tube, said conical back plate being of increasing diameter as it extends from said outboard end; first and second reinforcing rings circumferentially encompassing opposite ends of said conical back plate; and wherein a center of mass of at least one of said first and second reinforcing rings is toward the outboard end of the torque tube and conical back plate assembly from a midplane projection of said conical back plate.